docs: def count_elements(doc):
      "Counts the number of times each element is used in a document"
      summary = {}
      for el in doc.iter():
          try:
              namespace, element_name = re.search('^{(.+)}(.+)$', el.tag).groups()
          except:
              namespace = None
              element_name = el.tag
          if not summary.has_key(namespace):
              summary[namespace] = {}
          if not summary[namespace].has_key(element_name):
              summary[namespace][element_name] = 1
          else:
              summary[namespace][element_name] += 1
      return summary